Fox RC4 450g + Nukeproof Ti spring 235g
CCDB Air 530g
difference of 155g or 0.34lbs
£500 to drop 155g, dunno about that one
But that assumes you already have the RC4 and Ti spring. Think of it like this - The Dhx RC4 with steel spring is circa £480 + £139 for the Nuke proof Ti spring
CCDB Air £495
difference of £124 in favour of the Cane Creek.